A. Field of the Invention
The field of the present invention relates generally to continuous belt systems configured for carrying bulk materials thereon. More particularly, the present invention relates to such continuous belt systems having a plurality of return roller assemblies supporting the conveyor belt during its return fligh. Even more particularly the present invention relates to a return roller assembly having a solid shaft connected to sealed bearings.
B. Background
Continuous belt conveyor systems are commonly utilized to carry bulk materials, including trash, recyclables, gravel, coal, aggregate and many other types of materials, from one location to another, sometimes over long distances. One well known configuration for such conveyor systems has a continuous belt that comprises an upper flight section which carries the bulk materials to a location where it is dumped off the end of the conveyor belt for disposal or further processing and a lower flight section that returns the belt to a position where it can receive more bulk materials. A supporting framework supports roller assemblies, placed at appropriate intervals, over which the generally flexible belt travels in the upper and lower flight sections. To better maintain the bulk materials on the belt when traveling through the upper flight section, it is common to arrange the roller assemblies in the upper flight section in a generally trough or trough-like cross section that defines the belt in a corresponding configuration. These roller assemblies are commonly referred to as trough roller assemblies. The lower flight section is typically supported by roller assemblies comprising a single roller that supports the flexible belt in a generally flat or horizontal configuration. These roller assemblies are commonly referred to as return roller assemblies.
The present invention is directed to an improved return roller assembly for supporting and directing the conveyor belt during its return flight. The prior art return roller assemblies generally comprise an elongated tubular roller having a shaft and bearings, disposed in the roller, that allow the roller to freely rotate with the movement of the belt against surface of the roller. The ends of the shaft extend outwardly from the ends of the roller and attach to brackets that transversely support the roller between a pair of frame members which comprise the framework that supports the continuous belt conveyor system. In a common configuration, as exemplified in U.S. Pat. No. 3,212,626 to McLeish, et al. and U.S. Pat. No. 3,105,588 to Long, a single roller extends the entire length between the brackets to support the belt, which are typically provided in widths of 24, 30, 36 and 48 inches. These return roller assemblies have some well known problems that the present invention overcomes. The primary problem results from the fact that the existing roller assemblies utilize bearings that cannot be greased. Because the rotating ends of the rollers are exposed where they connect to the bearings and brackets, they are known to become clogged with debris, typically from the bulk materials being transferred over the upper flight section. As an example, in recycling operations where the conveying system is utilized to convey waste materials for further processing, it is well known that waste particles can clog the bearings. Problems with other materials are also well known. When the bearings become clogged, they freeze-up and stop rotating. When this happens the belt is then sliding over a stationary roller, which has a relatively thin metal shell that, over time, is gradually ablated away. If not fixed, the roller will form jagged edges that cut into the conveyor belt. Avoiding clogging of the ends of the rollers require frequent maintenance in order to prevent damage to the rollers, belt and the belt system itself. Even with frequent maintenance the rollers typically require frequent replacement. In addition to the direct cost of purchasing new rollers and installing the rollers, clogging of the rollers in the return roller assembly significantly impacts the efficient operation of the belt system and, therefore, the use or processing of the bulk materials.
Another problem that is well known with the single tubular roller for the return roller assembly is that the edges of the belt tend to cut into the roller, which forms holes in the roller that necessitate its replacement before it significantly damages the belt. This problem results from the fact that the troughing rollers which are commonly utilized to support the belt in the upper flight section tend to impart a trough-like cross section to the belt itself. On the return flight, the belt is upside down relative to the upper flight, causing the edges of the belt to cut into the tubular return roller and damage the edges of the belt. U.S. Pat. No. 5,373,935 to Anderson describes a return roller assembly for a bulk conveyor system that attempts to overcome this problem by providing three rollers that are configured in an inverted trough-like shape to match the shape of the belt. The three rollers are separately supported by brackets that attach to a transverse support member. While the assembly of the Anderson patent attempts to address the issue of the belt having a trough-like shape in an attempt to eliminate the belt cutting into the roller, it does not address the issue of the exposed bearings in the roller and the problems associated with clogging. In fact, due to the number of rollers used in that assembly, the likelihood of this problem is likely increased.
What is needed, therefore, is an improved configuration for a return roller assembly that substantially reduces or eliminates debris clogging the rotating mechanism, a problem which is prevalent among presently available return roller assemblies. The preferred return roller assembly should substantially shield the rotating connections from being clogged with debris or other material so as to reduce the need for maintenance and/or replacement of the bearings and rollers. The preferred return roller assembly should comprise a minimum number of moving parts and be adaptable for a variety of different types of belts and conveyor system configurations. Preferably, the improved return roller assembly will be adaptable to being manufactured out of materials and components that provide a lower cost return roller assembly for use in various industrial and commercial enterprises.